Idle adjustment screw length?

I just rebuilt the carbs on my XJ650J Maxim and reassembled. All went well. The articles on this forum and parts from Xj4Ever are amazing.

After reassembly and bench syncing I feel the butterfly adjustment screws are tighter than I would expect. Also, the spring on the idle adjustment screw is fully compressed and the tip is barely touching the plate on the butterfly adjustment bracket between carbs 2/3 meaning I cannot screw it any more to adjust the idle on the carbs.

This was a set I bought to refurbish so am wondering if the screw is shorter than it is supposed to be or I missing something?

Thanks in advance.

 

It sure looks like the right screw, but certainly not in the correct position.
Can you move the butterflies open and close by hand?
Did you bench synch them? How about a picture of the butterflies and what position they are in?

 

I did bench syncing them following the post from this forum.

Uploaded pics of the butterfly positions.
Let me know if you need more pics or more detail.
Thanks again.

 

Best I can tell the idle adjustment screw on my Hitachi carbs is approximately 3 1/4" over all length, with the shoulder portion about 2" long.

 

Good detail. I will measure that to see if someone shortened it at some point. If it is the correct length I will recheck the bracket configurations.

 

look in this link to compare photos put on some shades
OWWW, My Eyes!



I do not think those 2 flat washers on the idle knob spring belong there,

whatt did you use to gauge the butterflies opening?

 

When you put the throttle plates back in, did you make sure that the screws were loose while you worked the throttle shafts so the plates would seat properly?
It looks to me like the throttle plates are jammed against the carb throats and that's what's holding the throttle stop so far forward.
#1, in particular, looks to be open far further than it should be after a bench synch.

 

By chance, did you mix-and-match parts from different carb sets? There are two different types of lower rack brackets for the XJ650 model carbs, and they differ in the length of the bracket that holds the idle speed bolt.......one type uses a rubber grommet to support the bolt, the other style does not use a grommet (metal-to-metal). If I recall correctly (Dave would know for sure!) they don't interchange between the sets.

 

Quite possible this was not done correctly. I will check this and try to re-seat them.

 

These were as I bought them. It is possible a previous owner mixed and matched. It would be good to know for sure on your question about the two styles/measurements. Can anyone verify the question on different brackets to hold the screw?

 

No grommet on my idle adjustment screw -81' XJ650 Maxim w/ Hitachi carbs.

 

K-moe: genius!
I just finished re-seating the butterflies and it is definitely better after bench syncing them.
Stumplifter and Chacal: Thanks for the knowledge.
If it is the wrong bracket would there be anything wrong with adding an extension to the screw? I just built an extension that I can use if there would be no issue in doing so. (Added an image of the extension.)

How compressed should the spring be when the end of the screw is barely touching the plate on initial set?
The screw threads are about halfway through and the spring is pretty compressed already.


View attachment 26437

 

those carbs in the pictures ain't bench synced, are they?
you always have to lower the idle as the running sync gets close, you might not have anything to worry about

 

I have tried to bench syncing them twice following the how-to on this site. Maybe I. Doing that wrong bases on initial state of the butterflies?

There are two sets of dots inside the body, which set should the butterfly be lined up with on initial setting? They were lined up with the set of 2 dots rather than the single do when I started.

 

The idle speed adjustment screw should be threaded in about halfway when you've got it bench synched. There has to be enough thread to get the screw started without there being any spring tension, and enough thread left to set the idle. Yours looks good to me, but get rid of the extension and put the spring back in. Without that spring the idle speed will change, and eventually the screw will fall out onto the road.

There are two fuel inlets (what I think you're referring to a dots). You set the butterflies to be about halfway across the hole that's closest to the mouth of the carb.

 

Awesome!

Back to the settings with threads about half-way through after bench syncing.

Spring was out to show thread availability for the screw (back in now).
... And I thought setting the floats was going to have been the most frustrating part ... It all started with valve adjustments ....

Now to try my luck at color tuning.

Love this forum. The most knowledgeable site around for bikes!

 

I do not think the washers belong on the idle knob screw that you have on both sides of the spring.
if you remove them you will have a less compressed spring and more travel length by 2 thickness of those washers.

any one else have washers on the idle knob spring?

 

No washers on mine.

 

Good eye. Those washers are for protecting the outside of the throttle shaft seals.

 

I thought that Chacal sold small thin plastic washers just for the idle adjustment screw to aid in turning the adjustment screw in or out.......even thou it is not original equip

 

I have the last time when i bench sync the same situation ,pls resync on bench again ,you didnt make wright sync .that washers arent original but you can live it on if you like.
I make wright benc sync following that thread
http://xj650.blogspot.si/2009/04/how-to-bench-synch-your-carbs.html?m=1

 

Correct!

 

Another upvote on that. That is why I bought them

 

This is the thread I followed. Issue is that I didn't see any description on what the idle screw should look like as far as depth being screwed in or out after a successful bench syncing. Great responses to all.

 

Just as far as it needs to be for the #3 throttle plate to partially cover that first fuel outlet. The Idle speed screw IS the synch screw for #3.

 

Thanks up, good description.